The invention relates to a trigger unit for initiating pyrotechnic elements.
By pyrotechnic elements are to be understood all elements which, as a result of the application of a electric voltage, preferably in correction with coded signals, trigger a pyrotechnic effect that has a desired result, for example the ignition of an explosive charge or the triggering of the gas generator of an air bag or belt tightener. Thus, inter alia fuses, in particular detonating fuses for civil and high-security domains (automotive, military and oil-field domains), ignition elements and gas generators belong to the pyrotechnic elements.
Electronic fuses whose ignition lines have commercially available plugs, for example DIN plugs, jack plugs, RCA plugs or BNC plugs, with which the electrical connection to the terminal lines of other fuses and the detonating machine is established, are known from EP 0 849 562 A2. These known electronic fuses each have an ignition line of a specific length which end initially in, for example, a jack plug. Emerging from this plug there is a further line (bus line) which ends in a plug socket that is compatible with the jack plug. The plug and plug socket of a fuse are wired in such a way that the individual poles are short-circuited when the former are plugged together. The fuses are delivered with plugs plugged into the socket. This is to provide protection against unintentional ignition, in particular in the case of an external voltage effect and high-frequency loading Before the fuse is assembled, the ignition line with the plugs connected thereto must be soldered onto the electronic circuit of the fuse.
Electric fuses in which the wires of the ignition line are embedded, in a twisted state, in the stopper sealing the housing of the fuse are known from DE-OS 28 24 568. A specific length of the ignition line is assigned to the fuse. If required, the components of a plug connection can be connected to this ignition line. Fuses equipped in such a way have the disadvantage that the ignition line attached thereto takes up more space and is heavier than the fuse itself.
Moreover, an ignition line that is already connected to the ignition means, for example an ignition cap, or to the hybrid containing the electronic components complicates the assembly of the fuses Before assembly of the known fuses, the ignition line must be soldered or welded onto the hybrid or the ignition cap. The ignition line that is coiled and which is substantially large in terms of volume and mass, hangs from these small dimensioned parts, on the flexurally slack wires, whereby manual assembly of the components of the fuses is complicated and mechanical assembly becomes expensive and has long cycle times.
It is therefore the object of the present invention to purpose a trigger unit for initiating pyrotechnic elements that can be produced in a rational manner.
The object is achieved by surrounding the switch and the control unit by a first housing case, the first housing case being connected to a second housing case which contains the charge body, and by having the ignition means go right into the second housing case.
Advantageous developments of the invention are claimed in the subclaims.
The trigger it in accordance with the invention for initiating pyrotechnic elements is composed of two housing cases. The first housing case surrounds a stitch and control unit, for example in the case of an unfinished or base fuse the so-called hybrid. The hybrid comprises inter alia the electronic circuit arrangements for addressing a fuse and, if applicable, for fixing the ignition point. Connected to this first housing case there is a second housing case which contain the charge body. This is, for example, in the case of a detonating fuse, the detonating capsule that is charged with the initiating detonating agent or, in the case of a belt tightener, the propellent charge for the generation of gas. Going right into this second housing case is the ignition means that is connected to the switch and control unit and which is not surrounded by the first housing case. The switch and control unit can consist of a printed circuit board on which sensitive electronic components are arranged. Owing to the fact that the switch and control unit is surrounded, in accordance with the invention, by a stable housing case, it can even be handled by automatic handling and loading machines for the mechanical assembly of a trigger unit without the electronic components being endangered. Moreover, storage and further processing are simple and inexpensive on account of the compact form.
Since the switch and control unit is surrounded by its own housing case, in view of the diameter of this housing case it is not necessary to pay any heed to the diameter of the housing case for the charge body. This is advantageous, for example, if the switch and control unit is accommodated in an IC package or, for example, bulky capacitors are used whose dimensions exceed the diameter of the housing case of the charge body. In this case, the diameter of the housing case for the switch and control unit can be greater than the diameter of the housing case for the charge body.
Owing to the fact that the charge body and the switch and control unit are arranged separately from each other in their own respective housing cases, it is possible, moreover, to surround the switch and control unit with a housing case that has a substantially greater wall thickness than the housing case of the charge body, for example the detonating capsule of a fuse. As a result of this equipping, the sensitive electronic components of the switch and control unit are not only protected against damage during handling, in the case of mechanical assembly, but also against the influences to which the trigger units are subject during their use. For example in the case of detonating fuses, in particular if, in the case of blasting at time intervals by detonating fuses, great dynamic pressure, shock and/or impact loads are exerted on the not yet ignited fuses, the so-called hybrid, the switch and control unit for fuse-addressing and for fixing the ignition point, is protected from these effects of pressure and impact on account of the greater wall thickness of the housing case before there is premature failure. The wall thickness and, in particular, the material of the housing case can be matched to the respective case of loading. So that an electronic fuse is optimumly protected against the effects of preceding fuse explosions, in particular with blasting at intervals, it is possible to avoid damage to the hybrid on account of pressure and shock effects in the beat possible way by means of the choice of the materials, for example steel, brass or copper. In order to be able to withstand the effects of the pressure in an optimum manner, in particular when there is blasting at intervals, the first housing case should withstand a dynamic pressure load of at least 100 MPa without deformation. Separate protection measures as used in the case of known fuses, for example the fitting of reinforcing or protecting tubes over the sensitive portion of the electronics unit, are superfluous.
In a further advantageous development of the invention, the switch and control unit is to be embedded in the first housing case in a hardened, non-metallic material. This can be effected in a preceding separate step of manufacture or, if the switch and control unit has been inserted into the first housing case, it is possible, for example, for plastics material, preferably polyvinyl chloride (PVC), polyurethane (PU) or else polyamides (PA), to be injection-moulded around it. Encapsulation, preferably with epoxy resins, is likewise possible. As a result of the injection-moulding or encapsulation, the switch and control unit is not just fixed in its position. The first housing case, as a result of being completely filled with the corresponding material, attains additional elastic rigidity against external pressure and shock effects.
The terminal contacts of the Switch and control unit are brought out of the first housing case at its two ends so that the electrical coupling for ignition is possible by way of a terminal to the ignition line, for example by means of a plug and plug socket, and to the ignition means, for example an ignition cap.
In a further advantageous development of the invention, the material that surrounds the switch and control unit can project from the first housing case in the form of a stopper at least on the side that faces the charge body, for example, a detonating capsule. This stopper is to be formed in such a way that it cam be inserted into the second housing case as a sealing and fastening element. In the case of mechanical assembly of the trigger unit, for example an electronic fuse, the first housing case with the stopper can be inserted into the second housing case with the charge body, for example a detonating capsule that is charged with initiating explosive. Then a connection can be established between the first and the second housing case, for example by adhering the stopper to the second housing case or by means of a form-locking connection by mechanical deformation of the second housing case, for example by swagging, camming action or crimping. The stopper, which, whilst projecting out of the first housing case, extends into the second housing case, assists the connection of the two housing cases and provides the connecting point with appropriate mechanical rigidity. Furthermore, it can be used to seal the second housing case, in particular, in a moisture-proof manner.
The first and the second housing case can be connected together in a form-locking, force-locking or substance-locking manner, in which case the mature of the connection depends upon the materials of the two housing cases, the loading that is to be expected during their use and also the handling when the two housing cases are brought together during assembly.
Instead of soldering the line for electrical coupling, for example an ignition line, directly onto the terminals of the switch and control unit that project out of the first housing case, the first housing case can also carry at its free end the coupling portion of a plug connection between the trigger unit and the line for the electrical coupling, the ignition line. As a result, the trigger unit no longer supports any line that is fixedly connected to it. A base fuse, for example, is, as a result, very compact in terms of its dimensions and can be equipped mechanically in a particularly advantageous manner, can be connected to the second housing case, to the detonating capsule, and subsequently can be packed.
Those materials, in particular, with which injection-moulding or casting around the switch and control unit in the first housing case is effected are suitable as the material for the coupling portion. The material, with which the first housing case is filled, can then assume the form of a plug socket or a plug at the free end of the housing case. When securing the coupling portion to the trigger unit, seceding of that coupling portion with which the line for electrical coupling, the ignition line, must be equipped, automatically follows.
Instead of moulding a coupling portion of a plug connection from the material in which the switch and control unit is embedded, it is also possible in the case of a fuse the detonating capsule to form the first housing case as a coupling portion at its end that is remote from the charge body. Thus, for example, the housing case can project beyond the cylindrical body with the switch and control unit that fills the housing case and can form a plug socket. In order to fix the plug of the line, it is possible to provide openings in the housing case wall into which spurs an the plug engage. In addition, other known elements that secure the plug connection can be provided. The advantage of this plug connection is the high level of stability and the protection against bending and in particular against kinking during the use of the trigger unit, in particular the fuse.
In a further development of the invention the coupling portions of the plug connection are each equipped with an orientation aid so that connection of the coupling portions is possible in just one orientation. As a result, when connecting the line to the electrical coupling, wrong connection are to be prevented from being established that could lead to the disturbance, failure or even to the unintentional self-ignition of the trigger unit. The orientation aids can be plug chicanes, for example. These are inter alia irregular cross sections of the plug and plug socket so that insertion is only possible in one orientation. In addition, the arrangement of the terminals can be used to form an orientation. If the plug and plug socket have a symmetrical cross section, the terminal pins or contact sleeves can, for example, be arranged in one diagonal in such a way that they are distributed across the respective cross section of the coupling portion or in such a pattern that even here it is only possible to couple the two coupling portions, plug and plug socket, in one orientation.
Further advantages emerge if the coupling portions of the trigger unit and the line for the electrical coupling are equipped with interlocking locking elements that establish a connection that is secured against being broken unintentionally. The locking elements, for example claws of so-called stop lamellae that engage into a groove, or a web ring that latches into the groove, a cap nut on the plug which is screwed together with the plug socket, or a bayonet catch, secure the two coupling portions, plug socket and plug, against being drawn apart unintentionally and thus undoing the connection. The plug connections of the fuses that are provided for rugged conditions in mines, quarries and in explorations, for example, are to be able to tolerate high tensile forces, as far as possible above 100 N, without the plug connection coming undone or the plug connection becoming loose.
In a further advantageous development of the invention, the coupling portions of the plug connection are equipped with sealing elements. Thus, for example, the contacts of the plug can be surrounded with a sealing ferrule which is accommodated and enclosed by the plug socket. The sealing ferrule is additionally covered by stop lamellae, the claws of which latch into a groove is of the plug socket. As a result of the plug connection that has been described, the contacts are protected against atmospheric influences, in particular against moisture, this being necessary, for example, for the use of detonating fuses in quarries, in mining and in explorations. The plug and plug socket can, for example, also be protected against the penetration of moisture by way of interconnected sealing rings.
In a further development of the invention, the number of contacts of the plug or the plug socket as well as their arrangement is matched to the use of the trigger unit. As a rule, two contacts suffice, although, for example in the case of detonating fuses, it can be necessary to provide more than two contacts, in a maser conditional on a special sequence of detonations or the arrangement of the fuses. Furthermore, the arrangement of the contacts can contribute to raking impossible a wrong connection of a plug or a plug socket.
The electronic control of the trigger unit, for example the setting of the ignition point of detonating fuses in the case of explosions at time intervals, is effected by means of semiconductor integrated circuits, with their modules being accommodated in an IC package in a further development of the invention. On account of the compact construction and the secure accommodation in the package it is possible to test the terminals of the IC by means of testing processes with a fuse function. IC-packages can easily be processed on prefabricated printed circuit boards on account of the terminals that are directed out in a defined manner. The use of encapsulated, prefabricated integrated circuits provides the advantage that these circuits are already tested at the site of their manufacture in all the temperature ranges in which use is possible so that no trigger needs to be singled out on account of a defective switch and control unit only after a trigger unit has been assembled. Whether for detonating fuses, belt tighteners or gas generators for air bags, the electronics unit may not have any defects. It is therefore more cost-effective to reject just the defective electronics unit (IC package) than it is to reject a complete trigger unit Moreover, the circuits that are accommodated in an IC package present special advantages in the case of automatic handling during the fitting of the printed circuit boards in chip on board technology on account of the high assembly) demands on the product.
In a further advantageous development of the invention at least the first housing case of the trigger unit has an identifying marking. The identifying marking can, for example, consist of a legible inscription or even of a bar code. It can contain the data that is relevant to the use of the trigger unit, for example the manufacturer, the type designation, the legal identification marking and, in the case of fuses, in addition, the time stage or the ID number.
The identifying marking does not need to be limited to the first housing case. It can also be applied to the second housing case. With separate manufacture of a switch and control unit, a base fuse, for example, and the charge body, for example a detonating capsule, when later brought together to form a trigger unit, an electronic fuse can result on account of the identifying marking on the two housing cases non-interchangeable association of the portions which can be assembled together.
The invention is explained in greater detail with reference to detonating fuses as an exemplifying embodiment. On account of the different structural forms of other trigger units, for example belt tighteners or gas generators of air bags, the embodiments can differ from one another.